The prior art includes a plurality of airfoiled blades for various applications. Such applications include blades specifically designed to reduce weight, blades specifically designed for use with commuter aircraft, and thin swept blades for reliable high speed performance.
For aircraft which use high speed turbo props, typical airfoiled blades available today allow for good cruise performance, but fall short on performance of the propeller at low aircraft speeds. Such shortcomings are essentially due to the failure of the industry to specifically design an airfoil for high speed turbo props which allows for improved performance of the propeller at low aircraft speeds while still maintaining good cruise performance at high speed. An airfoil design that can provide these characteristics would enhance the overall performance of the propeller blade and the aircraft.
Currently available airfoiled blades for aircraft include those shown in U.S. Pat. No. 4,830,574 to Wainauski et al, which discloses an airfoiled blade directed to minimizing propeller weight by utilizing narrow chord blades; U.S. Pat. No. 4,834,617 to Wainauski, which discloses an airfoiled blade which is thin swept having its application as a prop fan with high tip speed and mach numbers; U.S. Pat. No. 4,941,803 to Wainauski et al, which discloses an airfoiled blade designed for high loading and high efficiency at relatively high mach numbers; and U.S. Pat. No. 4,519,746 to Wainauski et al which discloses an airfoiled blade which is directed for use with commuter aircraft. As indicated in the above patents, none of these airfoil designs address the dual considerations of efficiency at low speed and at cruise speeds, both of which are associated with modern high speed turbo props.
There exists a need, therefore, for a new airfoil design for use with modern high speed turbo props, which perform efficiently at low aircraft speeds while also maintaining good performance at the high cruise speeds associated with the modern high speed turbo prop.